This keeps the application from freezing entirely.

The problem here would be that I don't get any calls to 'error' and I don't get
anything to catch. Of course it would be nice to just fix the glitch in either
CouchDB or jQuery but I don't really have time for this.
Reverted change of output format introduced by 05735634135c.
Revised _views/geojson key.

I thought about this and it is completely unnecessary to run this view through
a list if I use a more specific key. All the info is already at the client's
hand.
Improved client design.

- Geometry and documents are obtainted by POSTING to _view/geojson directly
  with a specified list of documents and geometries specified by detail level.
  This works way faster because CouchDB does not skip over unused detail
  levels.
- Coordinate offset is applied by the client but still used in
  _list/bbox-filter for geometry search. This should probably be left
  completely to the client for sake of clarity.
- The new update_geometry does not use the error parameter anymore, so may of
  the lambdas are gone.
- As implied by commit 05735634135c, we use doc arrays again. The 20-line check
  for different id sets is replaced by a simple array comparison.
This seems to catch CouchDB's internal server errors.

.. or whatever they are. I simplified the list function because this seems to
do the trick. Also the delay between _list and _view is no longer needed.